Clutch mechanism for typewriting machines



Jan. 4, 1938, H|L| 2,104,559

CLUTCH MECHANISM FOR TYPEWRITING MACHINES Filed Sept. 19, '1936 ATTORNEYPatented Jan. 4, 19 38 7 I UNITED STATES PALENT- OFFICE CLUTCH MECHANISMFOR MACHINES 1 James L. Hillis, Rochester, N. Y., assignor toInternational Business Machines Corporation, New York, N. Y., acorporation of New York Application September 19, 1936, Serial No.101,531

4 Claims. (Cl. 192'-68) This invention relates to typewriting machines,Fig. 3 in order to avoid the necessity for drawing particularly thepower carriage return clutch a major portion of the parts in this figurein mechanism. dotted lines.- The holes in frame II) for the Theprincipal object of the present invenscrews l3 are counterbored toreceive the heads of 5 tion is to provide a carriage return clutchmechathe screws.

nism which is cheaper to manufacture, more re- A bronze journal I5 ispressed into a hole IS in liable in its operation, and requires lessattention the inner or left-hand side of the gear housing by servicementhan prior carriage return clutch while a considerably larger hole [1concentric with mechanisms. the hole I6, is closed by a shouldered plugI8 into 10 An object is to provide an improved carriage which plug ispressed a bronze journal I9. The 10 return clutch which is designed toautomatically journal I9 is in axial alignment with the journalcompensate for wear of the clutch facing. 'I5 and the two journalssupport a short shaft 20. Another object is to provide a carriage returnThe plug I8 is secured to housing I2 by means clutch which is easilydisassembled for cleaning, of two screws (not shown) which are locatedon 13 repair, or replacement of worn parts. diametrically opposite sidesof the shaft 20 and 15 An object is to provide a carriage return clutchfits within the opening II. In order to prevent which requires onlyoccasional adjustment which the gear housing I2 and the parts carried orpartly may be efiected by a single adjusting means. supported by saidhousing from dropping when A further object is to provide a clutch inwhich screws I3 are removed, and also to prevent the one of the elementscomprises a simple disc of housing from shifting relative to frame III,a 20 material having high frictional characteristics shouldered pin 2|,pressed into a hole in said which may be easily replaced without the useof housing, fits closely but'not tightly in a hole in cement, rivets, orother securing means to inframe I0. Thus the pin 2| and the walls ofstall the element in the clutch. opening I I hold the housing I2 againstdisplace- An object is to provide a clutch having three ment relative toframe I0 yet permit removal of 25 engaging elements, two of which engageopsaid housing when desired.

posite faces of the third to provide a double grip- The left-hand end ofshaft 20 is provided with a ping action to increase the area of contactand transverse hole to receive a short pin 22 which reduce wear. is heldin its hole by a set screw 23. The shaft 20 Other objects, advantages,and features of the is also somewhat rounded at its left hand end to 30invention will be specifically pointed out in the fit in a tapering holein a plug 24 which is pressed following description and claims or willbe apinto the end of the power roller generally desigparent from a studyof the description, claims, nated 25 of which the plug 24 forms a part.

and drawing. The power roller 25, besides plug 24, also includes :25 Inthe drawing: a metallic tube 26 on which is forced a rubber shell Fig. lis a large scale vertical section through 21, and an oil throw-01f ring28 pressed on the tube the clutch. 2B. The plug 24 hasv a slot 29extending trans- Fig. 2 is a vertical section on, line 2-2 of versely ofthe shaft 20 and engaged by the pin 22 Fig. 1. which acts to key shaft20 to the powerroller 25. Fig. 3 is a perspective view of the carriageThe left-hand end of the power roller 25 is not 40 return mechanism.shown but is provided in a well known way with The numeral II]designates a portion of the suitable means whereby the left-hand end ofthe frame of a typewriting machine, for instance, power roller may bedropped and drawn to the the well knownlnternational power-operated leftto disengage the pin 22 from slot 29 for the typewriter (formerly knownas the Electropurpose of removing the powerroller from the 45 matic).This frame has a wide opening or machine. I i cut-away portion I I whichis open at the bottom. J ournaled in the upper part of housing l2, andSecured to the inside of the frame It), in alignextending at rightangles'to shaft 29, isa worm ment with and covering the opening II, isaworm 'drive shaft 30- having a worm 3| meshing with drive gear housingI2. This housing is fasaworm wheel 32 on shaft I9. The worm wheel is 50,tened to frame III by means of two screws like I3 preferably made ofsome material like hard fibre (Fig.1) passing throughholes in frame I0ador ,a resinous condensation material like jacent the vertical edges ofopening .Il and Bakelite andisspaced from the ends of journals threadedinto tapped holes I4 (Fig.3) in the hous- I5, I9 by washers 33 loose onshaft 20. The gear ing I2. The frame II) has not been shown in 32 iskeyed to shaft 20 by means of a pin 34 which fits loosely in atransverse hole in said shaft and also loosely fits in a slot moulded inthe gear. Shaft 38 is connected to the usual driving motor for thetypewriting machine, which motor rotates continuously while the machineis in operation, by means of a flexible sleeve (Fig. 3) pressed on theend of shaft}! and also on the end of the motor shaft. Thus the shaft 20and hence power roller 25 rotate continually in a clockwise direction(Figs. 2 and 3), while the machine is in use. The housing i2 is filledwith a suitable grease for purposes of lubrication.

The shaft 2ll-projects to the right outside of the frame l8 and the plugl8 has a flange 35 also projecting outside of the frame and concentricwith said shaft to provide an annular space between shaft 20 and saidplug. Loosely mounted on the shaft 20 is a tape spool or drum 31 havingan annular recess ,38 into which the flange 35 extends, the hub of thedrum extending into the annular space between shaft 20 and the flange.The hub of the drum 31 is spaced from the right hand end of the journali3 by means of a spacing washer 38 loose on shaft 20.

The drum 31 has a circumferential rectangular groove to provide flangesfor guiding the usual typewriter carriage return tape 4| which is woundonthe drum 31 between the walls of groove 48. One end of the tape 4| issecured to the drum 31 while the other end is connected to the carriage.Thus rotation of the drum 31 in a clockwise direction (Figs. 2 and 3)results in winding the tape 4| on the drum 31 and draws the typewritercarriage to a position to begin a new line.

In order to keep the tape 4| taut while the carriage is beingmanipulated by hand or is moving in letter spacing or tabulatingdirection, a spiral fiat spring 42 is provided in the annular recess 38.The outer end' of spring 42 is secured to the drum 31 while the innerend is provided with a hook-shaped portion 43 adapted to slip into aslot cut in the flange 35 as shown in Fig. 2. The spring 42 is bentinwardly toward the shaft 28 and is hooked into the slot in flange 35 byfirst pushing the drum 31 to the left along shaft 20 until the inner endof the spring strikes flange 35 and then rotating the drum in aclockwise direction until the hooked portion slips into the slot in theflange. The drum is then turned by hand until the right spring tensionis secured and then the tape is secured to the drum. The spring 42 tendsto turn drum 31 in a clockwise direction (Figs. 2 and 3) to wind up thetape but is not strong enough to move the carriage against the tensionof the usual spring motor used for producing the letter feeding andtabulating movements of the carriage. When these movements take place,the tape 42 is unwound from the drum 31, turning the lattercounterclockwise and winding the spring 42.

The drum 31 is connected to shaft 20 for the purpose of rotating thedrum to wind the tape 42, and thus return the carriage, by a novelclutch of which the tape drum may form part. For this purpose theright-hand -or outer face of the drum 31 is faced flat at right anglesto shaft 20 to form a clutch surface. The clutch comprises two drivenelements consisting of the drum 31 and a disc 44 and a driving element45 located between the driven elements, all mount- :3 on shaft 20.

The driving element 45 consists of a non-metallic disc, preferably madeof a relatively stiff material having high frictional characteristicssuch as the composition lining now commonly used in automobile clutchesand brakes. The disc 45 has a round hole loosely receiving shaft 28 andis slotted to provide diametrically opposite key-ways 48 cooperatingwith a pin 41 loosely mounted in a transverse hole in shaft 20 to keysaid disc to the shaft. The pin 41 loosely fits the keyways 45 to permitdisc 45 to slide on the shaft." a small amount for a purpose which willbe explained more fully hereinafter.

The disc 44 is not mounted directly on shaft 28 but is part of anassembly which is free to both rotate and slide on said shaft. Thisassembly consists of a short sleeve 48; the disc 44, which is mounted onthe sleeve; a multiprong spring 48; a washer 58; a nut 5i, which isscrewed on tightly fitting threads formed in sleeve 48; a thrust cap 52loosely fitting over the outer end of sleeve 48; and three pins 53. Thecentral hole in disc 44 is counterbored to form a shoulder whichcooperates with a shoulder formed in the inner end of sleeve 48. Thespring 43 has six prongs which press on the disc 44 near its peripheryand is clamped tightly against another shoulder in sleeve 48 by means ofthe washer 58 and nut 51. The two shoulders in sleeve 48 cooperatingwith disc 44 and spring 49, respectively, are spaced far enough apart topermit the sleeve 48 to move inwardly or to the left (Fig. 1) relativeto disc 44 when the thrust cap 52 is pushed in the same direction andmovement of disc 44 is obstructed.

The pins 53 slide freely in holes drilled in the right hand face of thedrum 31 and are equally spaced around the periphery of disc 44, as shownin Fig. 2. Disc 44 is also provided with three pins 54, which are alsoequally spaced around the periphery of the disc equal distances from thepins 53. Pins 54 are considerably shorter than the pins 53 so as to beincapable of touching the drum 31 and act merely as retainers for coilsprings 55 which are interposed between the drum 31 and disc 44. Springs55 press the driven elements 31, 44 of the clutch apart and thus opposemovement of these elements relative to each other to engage them withthe driving element 45 by pushing the thrust cap 52 and sleeve 48 to theleft. Pins 53 couple the driven elements 31, 44 together so that bothmust move in unison when the clutch is engaged. Normally disc 45, thedriving element of the clutch, rotates freely between the drivenelements 31, 44, suflicient clearance being provided between the partsfor this purpose.

When the thrust cap 52 is pushed inwardly, that is, toward the left inFig. l, the assembly carried by sleeve 48 moves inwardly and, after, asmall amount of idle movement due to the clearances, disc 44 presses thedisc 45 firmly against the face of the drum 31. If now the sleeve 48 ispressed still further inwardly spring 43 yields and permits the sleeveto move relatively to disc 44 whereby the coacting shoulders in the disc44 and sleeve 48 separate by the amount of the excess movement of thesleeve. Thus the three elements 31, 44, 45 will be held in engagement byspring 43 and the tape drum 31 will be rotated by shaft 28 to wind thetape 42 and return the carriage.

Secured to frame "I, adjacent an opening Illa in said frame, are twobrackets 55, 51, both being fastened to the frame by a common pair ofscrews 58. Bracket 55 extends downwardly from frame ID to a pointslightly above the outer end of sleeve 48, at which point is pivoted onemember of a two part lever 59, 50. Both of the members 59, 60 areloosely mounted on a pivot pin 6| riveted to bracket 56. The member 59has a round-nosed arm 62 engaging the center of the thrust cap 52 andits upper end has a slot 43 which is curved concentrically with thepivot pin 6|. The member 60 is L-shaped, with its longer arm pivoted bythe pin 6|, while at the apex formed by the two arms there is provided abolt 64 passing through a round hole in member 60 and the slot 63 inmember 59. Thus the two members 59, 60 are rigidly connected together toform an operating lever, one of whose arms is adjustable relative to theother.

Bracket 51 is bent inwardly through the opening Illa to a point directlyabove the housing l2. At this point a pivot pin 85 is riveted to thebracket 51 and supports a toggle lever 66 which extends outwardlythrough the opening No. A pair of toggle links 61, only one of which isshown in Fig. 1, interconnects the lever 66 with the shorter arm ofmember 60.

When the inner or left-hand arm of toggle lever 66 is drawn downwardly,the toggle comprising the outer arm of lever 66 and the pair of links 61is straightened and moved slightly beyond the dead center position ofthe toggle, the oil dead-center movement being limited by a curvedextension 68 formed in lever 66 engaging the shorter arm of member 60.This causes the two part lever 59-40 to rock clockwise (Fig. 1) and pushthe thrust cap 52 inwardly to engage the clutch elements. The reactionof spring 49 back through the sleeve 48 and lever 59-50 causes thetoggle to look beyond its dead center position with extension 68engaging the shorter arm of member 60. Thus the clutch is held inengaged position by locking the toggle slightly beyond its dead centerposition.

The members 59, 60 are 50 adjusted that, when the toggle is looked asdescribed, the sleeve 48 will occupy a position further inwardly fromthe one at which the clutch elements 31, 44, 45 firmly engage. In otherwords, the lever 5960 is designed to have a certain amount of overthrow.The reason for providing this overthrow is to allow for the natural wearon the engaging surfaces of the clutch-elements 31, 44, 45.

In a prior Patent No. 1,753,450 there is shown a carriage returnmechanism in which the clutch is operated by squeezing apart two thrustcollars designated 46, 41 in the patent. As there was practically noresiliency in the friction facing of the two clutch elements shown inthis patent, and the movement of the toggle past the dead centerposition resulted in a very slight relaxing of the pressure exerted bythe driving element on the driven element. a very close adjustment ofthe nuts 49 in the patent was necessary to produce the proper engagingpressure, particularly in view.

of the small amount of movement the operating lever was capable ofmoving the thrust collars. As only a small amount of power is availablefor moving the clutch to engaging position, a force multiplyingmechanism must be used whose mechanical advantage is one of force andnot distance.

In the course of several years practical experience with the clutchmechanism disclosed in the patent it has been found to require frequentadjustment, often requiring the attention of a serviceman once or twicea month. This is due to the fact that only a small amount of movement ofthe thrust collar 46 of the patent results in engagement of the clutchhence only a few thousandths of an inch wear of the engaging surfaces issuilicient to make the clutch slip.

slippage, while not immediately enough to prevent proper return of thecarriage or operation of the line space mechanism, causes the clutchfacing to wear so rapidly that in a very short time the clutch slips sobadly as to prevent complete return of the carriage or to cause only apartial operation of the line spacing mechanism with the result that thespacing between lines varies.

The clutch described herein has the important advantage over the onedescribed in the patent of providing an excess of movement of theoperating lever and causing the driving and driven elements to be heldresiliently in engagement so that the clutch facing can wear to aconsiderable extent before'slipping of the clutch makes necessaryadjustment or replacement of the clutch facing.

It is obvious from inspection of Fig. 1 that lever 5950 can be adjustedso the sleeve 48 can be madeto overthrow quite a considerable amount andthat wear on the faces of the disc 45 will only result in the spring 49automatically taking up the lost motion between the sleeve 48 and thedisc 45. In other words, the disc 45 would have to be very. badly wornbefore the shoulder on disc 44 could engage the shoulder on sleeve 48and prevent the disc 44 from pressing disc 45 into contact with drum 31.On the other hand, the clutch described in the patent may requireservice one or more times a month, depending on how frequently themachine is used, since a few thousandths of an inch wear of the clutchfacing is enough to cause slippage.

An advantage of the clutch mechanism described herein is that itdispenses with the need for the ball bearings and the adjusting means onthe shaft l6 of the patent, whereby the cost of the clutch mechanism isgreatly reduced. The elimination of the adjusting means just mentionedmakes it easier to replace the only part likely to wear to an extentsufiicient to make replacements necessary during the useful life of themachine, as the driving element45 may easily be removed by firstremoving screws 58 and then slipping the element 45, together with theassembly carried by sleeve 48, to the right (Fig. 1) off the shaft 20.After the worn element 45 has been replaced by a new one, the brackets56, 51 are fastened in place and member 59 adjusted relative to member60 to take care of the greater thickness of the new element 45.

Since the peripheral speed is greatest near the rim of the element 45,the wear is usually greatest at this point in friction clutches andthere is a tendency for the rim of the element to become thinner than atpoints nearer the shaft 20. If the element 45 were of uniform thicknessradially of shaft 20, the element 45 would tend to become convex thusreducing the area of contact and ultimately causing slippage. To reducethis effect to a minimum, both sides of the element 45 are provided withan annular recess 4511. In spite of these recesses, the total area ofcontact between the elements 31, 44, 45 is equal to or greater than in atwo element clutch of the type shown in the patent and having only twoengaging surfaces.

The clutch is engaged by power means manually controlled by a carriagereturn key I (Fig. 3) in substantially the same way as in Patent No.1,753,450. The key 10 is pivoted at H and controls the engagement of acam unit 12 with power roller 25. Cam unit 12 is connected by a link 13to the toggle lever 66 whereby the tog- -gie lever is-ac-tnated llQsailcan gnit to engage the clutch as described above wheneverkey'lf .-isdepressed. Since the toggle comprising lever 66 and links 81 looks theclutch in engaged position, a lever 14 controlled by the carriage isarranged to bend the toggle sutllciently beyond its dead center positionrte permit disengagement of the clutch when the carriage reaches aposition to begin a new line as determined by the marginal stop.

While there has been shown and described and pointed out the fundamentalnovel features of the invention as applied to a single embodiment itwill be understood that various omissions and substitutions and changesin the form and details of the.device illustrated and in its operationmay be made by those skilled in the art without departing from thespirit of the invention. It is the intention, therefore, to be limitedonly as indicated by the scope of the following claims.

What is claimed is:

1. In combination with a drive shaft, a pair of driven elements on saidshaft, a driving element on said shaft between said elements, means tokey said driving element to raid shaft adapted to permit movement of thedriving element relative to said shaft, means to interconnect saiddriven elements whereby the latter rotate in unison, saidinterconnecting means permitting one of the driven elements to movetoward the other axially of the shaft and during the course of saidmovement engage the driving element and force the latter into engagementwith the second driven element, a sleeve for slidably mounting one ofthe driven elements on said shaft, said sleeve having a shoulderengaging a shoulder in the driven element mounted on said sleeve,resilient means for holding said shoulders in engagement, said resilientmeans being operative to permit the shoulders to disengage when one ofthe driven elements is moved toward the other to engage the drivingelement, and means for moving one of said driven elements toward theother.

2. In combination with a shaft, three clutch elements mounted" on theshaft, means to connect the outer two elements together for rotation inunison and for sliding of one element relative to and axially of theshaft whereby one of the outer clutch elements'may be moved toward theother outer element to engage the central element and engage the latterwith the other outer element to clutch all three elements together forrotation in unison, a sleeve for slidably mounting one of the drivenelements on said shaft, said sleeve having a shoulder engaging ashoulder in the driven element mounted on said sleeve, resilient meansfor holding said shoulders in engagement, said resilient means beingoperative to permit the shoulders to disengage when one of the drivenelements is moved toward the other to engage the driving. element, andmeans for moving one of said driven elements toward the other.

3. In combination with a drive shaft, a pair of driven elements on saidshaft, a driving element on said shaft between the driven elements,means to connect the driving element to the shaft for rotation therewithand adapted to permit longitudinal movement of the driving element onsaid shaft, means to interconnect the driven elements for rotation inunison whereby one of the driven elements is movable toward the otheraxially of the shaft and during such movement engages the drivingelement to force the latter into engagement with the other drivenelement; means toslidably mount one of the driven elements on the shaft,said mounting means having a stop portion engaging a stop portion in thedriven element mounted thereon; resilient means for engaging the stopportions, said resilient means being operable to permit the stopportions to separate when the driving-and driven elements have becomeengaged and resiliently maintain said elements in driving engagement andmeans to move the mounting means longitudinally of the shaft whereby toengage the driving and driven elements.

4. In combination with a shaft, three clutch elements mounted on saidshaft, means to interconnect the outer two elements for rotation inunison and for sliding movement of one element relative to and axial ofthe shaft whereby one of the outer clutch elements may be moved towardthe other outer clutch element to engage the central element and toengage the central element with the other outer element for rotation ofall three in unison, a member slidably mounted on the shaft forsupporting one of the outer elements and having a stop portionengageable with a stop portion in the outer element mounted thereon,resilient means for maintaining the stop portions in engagement, saidresilient means when the slidable member is moved longitudinally of theshaft causing the clutch elements to be resiliently maintained inengagement, and means for moving the slidable member longitudinally toengage the clutch elements.

JAMES L. HILLIS.

